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OutOfMemory exception when loading large images

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Morten Nielsen

I have a problem when loading some pretty large images. The images are
~700mb uncompressed, and the two first times I load an image, everything
works fine.

Each time I'm done with an image, I force a Garbage Collection using
GC.Collect() and I can see in the task manager that resources are actually
being released.

The weird thing is that when I load the third image to process (it's the
same function called from a loop), I always get an OutOfMemory exception.
(note: the third image is not always the same image file)

Not even closing and disposing the worker thread and restarting it wil cut
it. I have to exit the whole application to make it run again without the
memory exception.

Any ideas on what I can do to prevent this is highly appreciated.

/Morten Nielsen
Email: http://www.iter.dk/contact.aspx

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Morten Nielsen

I'm sorry, it's obviously not ALWAYS the third image. Sometimes it happens
later in the loop.
I noticed a thing when processing the image before the image that creates an
OutOfMemory exception when loaded. The physical memory used is much larger
(the virtuel memory used is the same) than with the previous images. The
Garbage collection does clean this up just before the exception, but maybe
it gives a hint on what wrongs.

Again... it doesn't have anything to do with the actual image that is being
loaded. It loads just fine if it is processed a little earlier in the loop.

After garbage collecting the memory usage is always 12mb physical and 52mb
virtual. After loading the image (when it is succesful), the usage is 54mb
physical and 757mb virtual.

/Morten

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Michael Pearson

Are you calling Dispose() on your image object?

Michael

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Morten Nielsen

> Are you calling Dispose() on your image object?
Yup.

Forcing Garbage collection seems to help a bit (it doesn't happen just as
often).

/Morten

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fd123456

Hi Morten,

Not sure at all it works, but it might help... Try :

GC.WaitForPendingFinalizers();

....right after your GC.Collect(). It suspends execution until all
finalizers have done their magic. If you have for instance 512 MB of
RAM, then your total memory (including virtual memory) is around 1500
MB, which means that two of your images cannot possibly be held in
memory at the same time (taking into account the 200MB+ that a
"normal" system occupies). Maybe waiting for the GC to have released
the memory could solve your problem.

HTH.

Michel

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David Notario [MSFT] (VIP)

Are you just allocating a big 700 Mb chunk? If yes, you are going to have
problems finding 700 contiguous Mb in virtual address space, you may want to
split the image into more manageable chunks

Have you tried Allocation profiler? Maybe there are unexpected referenced
objects

--
David Notario
Software Design Engineer, CLR JIT Compiler
http://devdiary.xplsv.com

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